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https://issues.apache.org/jira/browse/HADOOP-10161?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13850059#comment-13850059
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Yang He commented on HADOOP-10161:
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Colin Patrick McCabe , it is really necessary, especially for hbase users.
e.g. when a region is splitted to two new ones, the old metrics of the region
is invalid, but the metics are still here ,they also store values to disk ,the
invalid data will Increase disk pressure (io speed,disk space and so on).
Just changing the default value could't meet our needs in some case:defferent
types of metric may be configured different collecting period,so they need
diffirent dmax, we should and must easily configure them.
e.g:
Scenario 1: Config different default value for different metric types
#
datanode.sink.ganglia2.dmax_default=150
datanode.sink.ganglia2.context=dfs
datanode.sink.ganglia2.servers=10.28.171.212:8661
datanode.sink.ganglia3.dmax_default=130
datanode.sink.ganglia3.context=rpm
datanode.sink.ganglia3.servers=10.28.171.212:8661
Scenario 2: Change the default value of dmax for all metrics
#
datanode.sink.ganglia.dmax_default=130
datanode.sink.ganglia.servers=10.28.171.212:8661
Scenario 3: Keep the default value of dmax
datanode.sink.ganglia.class=org.apache.hadoop.metrics2.sink.ganglia.GangliaSink31
datanode.sink.ganglia.period=10
datanode.sink.ganglia.servers=10.28.171.212:8661
> Add a method to change the default value of dmax in hadoop.properties
> ---------------------------------------------------------------------
>
> Key: HADOOP-10161
> URL: https://issues.apache.org/jira/browse/HADOOP-10161
> Project: Hadoop Common
> Issue Type: Improvement
> Components: metrics
> Affects Versions: 2.2.0
> Reporter: Yang He
> Attachments: HADOOP-10161_0_20131211.patch,
> hadoop-metrics.properties, hadoop-metrics2.properties
>
>
> The property of dmax in ganglia is a configurable time to rotate metrics.
> Therefore, no more value of the metric will be emit to the gmond, after
> 'dmax' seconds, then gmond will destroy the metric in memory. In Hadoop
> metrics framework, the default value of 'dmax' is 0. It means the gmond will
> never destroy the metric although the metric is disappeared. The gmetad
> daemon also does not delete the rrdtool file forever.
> We need to add a method to configure the default value of dmax for all
> metrics in hadoop.properties.
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